Identification and antifungal susceptibility of penicillium-like fungi from clinical samples in the United States

Penicillium species are some of the most common fungi observed worldwide and have an important economic impact as well as being occasional agents of human and animal mycoses. A total of 118 isolates thought to belong to the genus Penicillium based on morphological features were obtained from the Fungus Testing Laboratory at the University of Texas Health Science Center in San Antonio (United States). The isolates were studied phenotypically using standard growth conditions. Molecular identification was made using two genetic markers, the internal transcribed spacer (ITS) and a fragment of the +-tubulin gene. In order to assess phylogenetic relationships, maximum likelihood and Bayesian inference assessments were used. Antifungal susceptibility testing was performed according to CLSI document M38-A2 for nine antifungal drugs. The isolates were identified within three genera, i.e., Penicillium, Talaromyces, and Rasamsonia. The most frequent species in our study were Penicillium rubens, P. citrinum, and Talaromyces amestolkiae. The potent in vitro activity of amphotericin B (AMB) and terbinafine (TRB) and of the echinocandins against Penicillium and Talaromyces species might offer a good therapeutic alternative for the treatment of infections caused by these fungi.